NATO coalition forces confirmed the rescue of four humanitarian aid workers Saturday, who were being held by Afghan militants in a cave in the country's northern-most Badakhshan province.

A NATO press release said that two Western doctors and two Afghan civilians were rescued in an early morning military operation.

"The rescue team was inserted by helicopter, under cover of darkness, and confirmed the presence of the hostages. After securing the location, ISAF forces conducted the rescue mission and successfully freed all four hostages," coalition forces spokesperson Lieutenant Lauren Rago said, describing the raid.

The aid workers, working for a Swiss-based humanitarian organization, Medair, were kidnapped May 22 while traveling by horseback to treat villagers suffering from malnutrition.

Medair's spokesman in Switzerland, Aurelien Demaurex, identified the victims as Briton Helen Johnston, 28, and Kenyan Moragwa Oirere, 26. The group did not reveal the names of the two local Afghan staff, but said it was "relieved and immensely grateful to everyone involved in their safe return."

According to the head of the U.S. and NATO forces in Afghanistan, U.S. General John Allen, the rescue operation was conducted with the support of the Afghan Interior Ministry. Afghan officials said all five hostage takers were killed in the raid.

Afghan Foreign Office spokesman Janan Musazia welcomed the release of the medical aid workers who, he said, were serving the people of Afghanistan and said he was "pleased with the outcome of the raid.

British forces took part in the operation, authorized by Prime Minister David Cameron. He described the rescue as "extraordinarily brave" and "breathtaking." The rescue team did not suffer any casualties in the operation.

It was not immediately clear what demands the kidnappers made.

In violence Saturday, NATO said one of its service members was killed in an insurgent attack in southern Afghanistan.

Sharon Behn is a foreign correspondent working out of Voice of America’s headquarters in Washington D.C Her current beat focuses on political, security and humanitarian developments in Iraq, Syria and Turkey. Follow Sharon on Twitter and on Facebook.